Method for manufacturing an article and injection molding system

Abstract

To provide an advantageous technique for suppressing a leakage of a resin.SOLUTION: A method for manufacturing an article using injection molding comprises: an injection step for injecting a resin into a cavity 104 of a mold 100A via a sprue 115 of the mold 100A from an injection nozzle 52 having a valve pin 56; an intermediate step for inserting the valve pin 56 of the injection nozzle 52 into the sprue 115 after the injection step, and pulling the valve pin 56 of the injection nozzle 52 out of the sprue 115; and an injection step for injecting a resin into a cavity 104 of a mold 100B via a sprue 115 of the mold 100B from the injection nozzle 52 after the intermediate step.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to injection molding. [Background technology]

[0002] In an injection molding system that performs injection molding, it is preferable to suppress leakage of resin from the injection nozzle. Patent Document 1 discloses that a valve pin provided on the nozzle is used to close the discharge port. Patent Document 1 also discloses that long strings of resin are generated between the mold and the nozzle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-081346 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technique of Patent Document 1 does not sufficiently consider how to suppress leakage of resin. Therefore, an object of the present invention is to provide a technique that is advantageous in suppressing leakage of resin. [Means for solving the problem]

[0005] A first aspect of the means for solving the above problem is a method for manufacturing an article using injection molding, characterized in having: a first step of injecting resin from an injection nozzle having a valve pin through a runner of a first mold into a cavity of the first mold; a second step of inserting the valve pin of the injection nozzle into the runner and removing the valve pin of the injection nozzle from the runner after the first step; and a third step of injecting resin from the injection nozzle through the runner of a second mold into the cavity of the second mold after the second step.

[0006] A second aspect of the means for solving the above-mentioned problems is a method for manufacturing an article using injection molding, comprising: a first step of injecting resin from an injection nozzle having a valve pin through a runner of a mold into a cavity of the mold; and a second step of inserting the valve pin of the injection nozzle into the runner and removing the valve pin of the injection nozzle from the runner after the first step, wherein the runner is a cold runner.

[0007] A third aspect of the means for solving the above-mentioned problems is a method for manufacturing an article using injection molding, comprising: a first step of injecting resin from an injection nozzle through a runner of a mold having a valve pin into a cavity of the mold; and a second step, subsequent to the first step, of inserting the valve pin of the mold into a resin flow path of the injection nozzle and removing the valve pin of the mold from the resin flow path.

[0008] A fourth aspect of the means for solving the above problem is an injection molding system comprising an injection nozzle and a transport mechanism for transporting a plurality of molds, wherein the injection nozzle has a valve pin for opening and closing a resin flow path, and when the resin flow path of the injection nozzle is closed by the valve pin, the valve pin protrudes beyond the tip of the injection nozzle when the resin flow path of the injection nozzle is opened. Effect of the Invention

[0009] According to the present invention, it is possible to provide a technique that is advantageous in suppressing leakage of resin. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an injection molding system. [Diagram 2] FIG. 2 is a schematic diagram illustrating the configuration of an injection nozzle and a mold. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5]FIG. [Figure 6] FIG. [Figure 7] FIG. 4 is a schematic diagram illustrating the shape of a tip of a valve pin. [Figure 8] FIG. 1 is a schematic diagram illustrating an injection molding system. [Figure 9] FIG. 1 is a schematic diagram illustrating an injection molding system. [Figure 10] Schematic diagram illustrating a manufacturing method. [Figure 11] Schematic diagram illustrating a manufacturing method. [Figure 12] Schematic diagram illustrating a manufacturing method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description and drawings, common reference numerals are used to designate components common to multiple drawings. Therefore, common components will be described with mutual reference to multiple drawings, and descriptions of components with common reference numerals will be omitted as appropriate.

[0012] <System Overview> 1 is a plan view of an example of an injection molding system 1 that can be used to carry out the invention. The injection molding system 1 of this example is a system that includes a horizontal injection molding machine 2, conveying devices 3A and 3B, and a control device 4, and manufactures resin molded products by replacing multiple molds with one injection molding machine 2 using the conveying devices 3A and 3B. A resin molded product is an article manufactured by injection molding.

[0013] The injection molding machine 2 includes an injection device 5. The injection device 5 includes an injection cylinder 51 and an injection nozzle 52. The resin molten in the injection cylinder 51 can be injected from the injection nozzle 52.

[0014] In the present embodiment, two molds 100A and 100B are used. The molds 100A and 100B may be collectively referred to as molds 100. The transport device 3A and the transport device 3B may be collectively referred to as the transport mechanism 3. By using the transport device 3A and the transport device 3B appropriately, the transport mechanism 3 can transport a plurality of molds 100A and 100B.

[0015] The mold 100 is a set of a fixed mold 101 and a movable mold 102 that opens and closes relative to the fixed mold 101. A resin molded product is formed by injecting molten resin into a cavity formed between the fixed mold 101 and the movable mold 102. Mounting plates 101a and 102a are fixed to the fixed mold 101 and the movable mold 102, respectively. The mounting plates 101a and 102a are used to lock the mold 100 at a molding operation position 11 (mold mounting position) of the injection molding machine.

[0016] The conveying device 3A carries the mold 100A into and out of the molding operation position 11 of the injection molding machine 2. The conveying device 3B carries the mold 100B into and out of the molding operation position 11. The conveying device 3A, the injection molding machine 2, and the conveying device 3B are arranged in this order in the X direction. That is, the conveying device 3A and the conveying device 3B are arranged on the left and right of the injection molding machine 2 so as to sandwich the injection molding machine 2 in the X direction. The conveying device 3A and the conveying device 3B are arranged opposite each other, with the conveying device 3A being arranged adjacent to one of the left and right sides of the injection molding machine 2 and the conveying device 3B being arranged adjacent to the other side. The molding operation position 11 is located between the conveying device 3A and the conveying device 3B.

[0017] Each of the transport devices 3A and 3B includes a frame 30, a transport unit 31, a plurality of rollers 32, and a plurality of rollers 33. Each of the transport devices 3A and 3B may be a cart that transports the mold 100 within a factory.

[0018] The frame 30 constitutes the skeleton of the apparatus, and supports a transport unit 31 and a plurality of rollers 32 and 33. The transport unit 31 is a device that moves the mold 100 back and forth in the X direction to put the mold 100 in and take it out of the molding operation position 11.

[0019] In this embodiment, the transport unit 31 is an electric cylinder driven by a motor, and includes a rod that moves forward and backward relative to the cylinder, the cylinder is fixed to the frame 30, and the fixed mold 101 is fixed to the end of the rod. The transport unit 31 can be either a fluid actuator or an electric actuator, but by using an electric actuator, the accuracy of controlling the position and speed of the mold 100 during transport can be improved. Examples of fluid actuators include hydraulic cylinders and air cylinders. Examples of electric actuators include, in addition to electric cylinders, rack and pinion mechanisms driven by a motor and ball screw mechanisms driven by a motor.

[0020] In this embodiment, the transport unit 31 is provided independently for each of the transport devices 3A and 3B. However, a common support member for supporting the molds 100A and 100 may be used, and one common transport unit 31 may be provided for this support member. However, providing the transport unit 31 independently for each of the transport devices 3A and 3B as in this embodiment is advantageous in that it can accommodate cases where the movement strokes during transport are different between the molds 100A and 100B (for example, when the widths (widths in the X direction) of the molds are different). Also, providing the transport unit 31 independently for each of the transport devices 3A and 3B is advantageous in that it can accommodate cases where the thicknesses (widths in the Y direction) of the molds are different and the molds cannot be transported simultaneously.

[0021] The rollers 32 form a roller row arranged in the X direction, and in this embodiment, they are arranged in two rows spaced apart in the Y direction. The rollers 32 rotate around a rotation axis in the Z direction, and come into contact with the side surfaces (side surfaces of the mounting plates 101a and 102a) of the mold 100 to support the mold 100 from the side and guide the movement of the mold 100 in the X direction. The rollers 33 form a roller row arranged in the X direction, and in this embodiment, they are arranged in two rows spaced apart in the Y direction. The rollers 33 rotate around a rotation axis in the Y direction, and support the bottom surface (bottom surfaces of the mounting plates 101a and 102a) of the mold 100 to support the mold 100 from below and smooth the movement of the mold 100 in the X direction.

[0022] The control device 4 includes a controller 41 that controls the injection molding machine 2, a controller 42A that controls the conveying device 3A, and a controller 42B that controls the conveying device 3B. Each of the controllers 41, 42A, and 42B includes, for example, a processor such as a CPU, a storage device such as a RAM, a ROM, or a hard disk, and an interface connected to a sensor or an actuator. The processor executes a program stored in the storage device. An example of the program (control) executed by the controller 41 will be described later. The controller 41 is communicably connected to the controllers 42A and 42B, and issues instructions to the controllers 42A and 42B regarding the conveyance of the mold 100. When the loading or unloading of the mold 100 is completed, the controllers 42A and 42B transmit an operation completion signal to the controller 41, and also transmit an emergency stop signal to the controller 41 when an abnormality occurs.

[0023] In this embodiment, a controller is provided for each of the injection molding machine 2, the conveying device 3A, and the conveying device 3B, but these three devices may be controlled by one controller. Also, in order to more reliably operate the conveying device 3A and the conveying device 3B in a coordinated manner, they may be controlled by one controller. By providing at least one controller for the injection molding machine 2 and one controller for the conveying device 3A and the conveying device 3B, the degree of freedom of the system is improved.

[0024] <Injection nozzle and mold> The configurations of the injection nozzle 52 and the mold 100 will be described with reference to Fig. 2(a) in addition to Fig. 1. Figs. 2(a) and (b) are cross-sectional views of the injection nozzle 52 and the mold 100 used in the injection molding system in an embodiment of the present invention.

[0025] 2(a) and (b), the injection nozzle 52 may have a valve pin 56 that can be positioned at the resin discharge port. The valve pin 56 is a rod-shaped or needle-shaped member, and may also be called a needle.

[0026] In Fig. 2(a), the mold 100 includes a mounting plate 101a of the fixed mold 101, a mounting plate 102a of the movable mold 102, a template 101b of the fixed mold 101, and a template 102b of the movable mold 102. The fixed mold 101 of the mold 100 is composed of the template 101a and the template 101b. The movable mold 102 of the mold 100 is composed of the mounting plate 102a and the template 102b. The mold 100 has a cavity 104 into which molten resin flows, and a sprue 115 and a cold runner 105 which serve as a resin flow path between the injection nozzle 52 and the cavity 104. The sprue 115 is an injection port for the resin in the mold 100. A mold 100 having a cold runner 105 has a structure (cold runner structure) in which no heating mechanism for heating the resin in the runner is provided around the runner (cold runner 105), which is a resin flow path within the mold 100.

[0027] Although an example of the valve pin operation process in S10 has been described for the mold 100 having a cold runner 105, the present embodiment will describe the case of a hot runner mold. Fig. 2(b) is a cross-sectional view of the mold used in the injection molding system of the present embodiment.

[0028] In FIG. 2(b), the mold 100 includes a mounting plate 101a of the fixed mold 101, a mounting plate 102a of the movable mold 102, a first mold plate 101b of the fixed mold 101, and a second mold plate 101c of the fixed mold 101. The mold 100 includes a mold plate 102b of the movable mold 102. The fixed mold 101 of the mold 100 is composed of the mounting plate 101a, the first mold plate 101b, and the second mold plate 101c. The movable mold 102 of the mold 100 is composed of the mounting plate 102a and the mold plate 102b. The mold 100 has a sprue 115 into which molten resin flows, a hot runner 114, and a cavity 104. The sprue 115 is an injection port for the resin in the mold 100. The mold 100 having the hot runner 114 has a structure (hot runner structure) in which a heating mechanism for heating the resin in the runner is provided around the runner (hot runner 114), which is a resin flow path within the mold 100.

[0029] The mold 100 includes a sprue bush 105, a manifold 106, a body 107, and ring-shaped holding members 108 and 109 for holding the manifold 106 in the mold 100, which are used to realize a hot runner structure. The sprue 115 and the hot runner 114 are resin flow paths between the injection nozzle 52 and the cavity 104. The mold 100 has a valve pin 110 that seals the resin injection port from the hot runner 114 to the cavity 104. The mold 100 has a valve pin 111 that seals the injection port (sprue 115) from the injection nozzle 52 to the hot runner 114. The valve pin 111 is a rod-shaped or needle-shaped member, and can also be called a needle. The cylinder 112 drives the valve pin 110. The cylinder 113 drives the valve pin 111. The hot runner structure of this mold 100 is realized by a sprue bushing 105, a manifold 106, a body 107, holding members 108 and 109, valve pins 110 and 111, and cylinders 112 and 113.

[0030] <Production method overview> The method for manufacturing an article using injection molding includes an injection process in which resin is injected from the injection nozzle 52 through the resin flow path of the mold 100 into the cavity 104 of the mold 100. Here, the resin flow path of the mold 100 is a sprue 115 and / or a runner (cold runner 105 or hot runner 114). This injection process is repeated to manufacture a plurality of resin molded products. In a first method, after the injection process is performed on the mold 100A, the mold 100A mounted on the injection device 5 is replaced with the mold 100B, and the next injection process can be performed on the mold 100B. In a second method, after the injection process is performed on the mold 100A, the resin molded product is removed from the mold 100A mounted on the injection device 5, and the next injection process can be performed on the mold 100A again. The first method is preferable because the above-mentioned conveying mechanism 3 makes it easy to replace the mold 100A and the mold 100B.

[0031] The manufacturing method of this embodiment has a feature in that it has an intermediate step between the previous injection step and the next injection step. The intermediate step is performed after the previous injection step, and the next injection step is performed after the intermediate step. The resin in the injection device 5 may be replaced between the previous injection step and the next injection step, but typically, a common resin can be used in the previous injection step and the next injection step. Typically, in the injection step following the previous injection step, the resin present in the resin flow path of the injection nozzle 52 at the intermediate step following the previous injection step is injected in the next injection step.

[0032] In the intermediate step, it is preferable to insert the valve pin 56 of the injection nozzle 52 into the resin flow path of the mold 100 and remove the valve pin 56 of the injection nozzle 52 from the resin flow path of the mold 100. By performing such an intermediate step, the resin remaining in the resin flow path of the mold 100 in the previous injection step can be pushed into the mold 100 by the valve pin 56, thereby reducing resin leakage between the injection nozzle 52 and the mold 100. The resin flow path of the mold 100 into and out of which the valve pin 56 is inserted is, for example, the sprue 115, but it may also be a runner (cold runner 105 or hot runner 114).

[0033] It is also preferable that, in the intermediate step, the valve pin 111 of the mold 100 is inserted into the outlet of the injection nozzle 52 and the valve pin 111 of the mold 100 is removed from the outlet of the injection nozzle 52. By performing such an intermediate step, the resin remaining in the outlet of the injection nozzle 52 in the previous injection step can be pushed into the injection nozzle 52 by the valve pin 111, thereby reducing resin leakage between the injection nozzle 52 and the mold 100.

[0034] In the intermediate step, only one of the insertion and removal of the valve pin 56 and the insertion and removal of the valve pin 111 may be performed, or both may be performed. When both the insertion and removal of the valve pin 56 and the insertion and removal of the valve pin 111 are performed in the intermediate step, the insertion and removal of the valve pin 56 may be performed before or after the insertion and removal of the valve pin 111, but is preferably performed before. When both the valve pin 56 and the valve pin 111 are present, it is preferable that the valve pin 56 and the valve pin 111 contact each other in the intermediate step. It is also preferable that the valve pin 56 and / or the valve pin 111 are removed while maintaining the state in which the valve pin 56 and the valve pin 111 are in contact with each other. The tip of the valve pin 56 and the tip of the valve pin 111 may be fitted into each other. In the intermediate step, it is desirable to include a state in which the resin flow path of the injection nozzle 52 and the resin flow path (cold runner 105 or hot runner 114) of the mold 100 are closed. In addition, in the intermediate step, when the valve pin 111 is inserted into and removed from the injection nozzle 52, the valve pin 56 of the injection nozzle 52 does not have to be provided.

[0035] The mold 100 used in the injection step before the intermediate step may have a cold runner structure or a hot runner structure. The mold 100 used in the injection step after the intermediate step may also have a cold runner structure or a hot runner structure. The mold 100 used in the injection step before the intermediate step may have one of the cold runner structure and the hot runner structure, and the mold 100 used in the injection step after the intermediate step may have the other of the cold runner structure and the hot runner structure.

[0036] In addition, in the intermediate step, the distance between the injection nozzle 52 and the mold 100 is increased (the injection nozzle 52 and the mold 100 are separated) in order to move to the next injection step. Since the amount of resin remaining near the boundary between the injection nozzle 52 and the mold 100 is reduced, it is possible to suppress the stringing of the resin between the injection nozzle 52 and the mold 100 when the distance between the injection nozzle 52 and the mold 100 is increased. Note that this operation of increasing the distance between the injection nozzle 52 and the mold 100 is performed after the valve pin 56 is removed from the runner 105. After It is preferable to perform this operation while the valve pin 56 is inserted. If the distance between the injection nozzle 52 and the mold 100 is increased while the valve pin 56 is inserted, the valve pin 56 may be damaged. However, if the distance between the injection nozzle 52 and the mold 100 is increased while the valve pin 56 is removed, the possibility of damaging the valve pin 56 can be reduced. For the same reason, the operation of increasing the distance between the injection nozzle 52 and the mold 100 is performed while the valve pin 111 is being removed from the resin flow path of the injection nozzle 52. After It is preferable that the valve pin 56 closes the discharge port of the injection nozzle 52 during the period from when the injection nozzle 52 is separated from the mold 100 until the start of the next injection step. This makes it possible to prevent the resin from leaking out of the injection nozzle 52 during the intermediate step. For the same reason, it is preferable that the valve pin 111 closes the injection port of the hot runner 114 during the period from when the injection nozzle 52 is separated from the mold 100 until the start of the next injection step.

[0037] The processing in the intermediate step will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the valve pin operation processing of the injection unit-related processing in S10. Figs. 4(a) to (c) are diagrams showing an example of the operation of the valve pin. The explanation will be given with reference to each step of the processing example in Fig. 3 and each state in Figs. 4(a) to (c). Note that in Fig. 3, the valve pin 56 of the injection nozzle 52 is abbreviated to nozzle pin, and the valve pin 111 of the mold 100 is abbreviated to mold pin.

[0038] [First embodiment] In S31 of Fig. 3, the process is divided depending on whether the mold 100 has a cold runner (CR) or a hot runner (HR). In this embodiment, the mold 100 having a cold runner (CR) is used, so the process of S32 is started. During the injection and pressure holding steps, the valve pin 56 is stopped at the retraction limit in the resin flow path of the injection nozzle 52. When pressure holding is completed, the valve pin 56 starts moving in the direction to close the discharge port 52a of the injection nozzle 52. In S32, the valve pin 56 starts moving from the retraction limit. Figure 4(a) shows this operation.

[0039] In S33, the valve pin 56 stops at the forward limit. Figure 4(b) shows this operation. The valve pin 56 passes through the outlet 52a of the injection nozzle 52, and is inserted into the flow path 105 in the mold that becomes the cold runner, where it stops. The insertion amount of the valve pin 56 is adjusted according to the resin capacity of the outlet 52a of the injection nozzle 52.

[0040] In S34, the valve pin 56 is removed from the sprue 115. Figure 4(c) shows this operation. The valve pin 56 retracts toward the injection nozzle 52, moves to the nozzle touch portion, and stops. The valve pin 56 is not inserted into the sprue 115, but blocks the discharge port 52a of the injection nozzle 52. The position of the valve pin 56 at this time is called the separation position.

[0041] In S38, with the valve pin 56 closing the discharge port 52a of the injection nozzle 52, the injection nozzle 52 is retracted. In other words, the distance between the injection nozzle 52 and the mold 100 is increased. Figure 4(d) shows this operation. As a result, the injection nozzle 52 is separated from the mold 100.

[0042] Thereafter, the valve pin 56 remains in the separated position until the start of the next injection process. When the injection process starts, the valve pin 56 is moved from the separated position to its retracted limit and resin is injected from the discharge port 52a of the injection nozzle 52.

[0043] [Second embodiment] An example of the operation of the valve pin in the case of a hot runner mold will be described with reference to FIG. 3 and each state of FIGS. 5(a) to (c).

[0044] 3, the process is divided depending on whether the mold 100 has a cold runner (CR) or a hot runner (HR). In this embodiment, the mold 100 having a hot runner is used, so the process of S35 is started.

[0045] In S35, the valve pin 56 starts moving from its rearmost position. Figure 5(a) shows this operation. During the injection and pressure holding processes, the valve pin 56 is stopped at its rearmost position in the resin flow path of the injection nozzle 52. When pressure holding is completed, the valve pin 56 starts moving in the direction to close the discharge port 52a of the injection nozzle 52.

[0046] In S36, valve pin 56 comes into contact with valve pin 111 and stops. Figure 5(b) shows this operation. Valve pin 56 passes through outlet 52a of injection nozzle 52, is inserted into the resin flow path (sprue 115) in mold 100, and comes into contact with valve pin 111 and stops.

[0047] In S37, the valve pin 56 is removed from the sprue 115. Figure 5(c) shows this operation. The valve pin 56 and the valve pin 111 move in close contact to the separation position and stop there. The valve pin 56 moves back in the direction to seal the discharge port 52a of the injection nozzle 52, and the valve pin 111 moves forward in the direction to seal the sprue 115, moving to the separation position, i.e., the nozzle touch portion, and stopping there.

[0048] In S38, with the valve pin 56 closing the discharge port 52a of the injection nozzle 52, the injection nozzle 52 is retracted. In other words, the distance between the injection nozzle 52 and the mold 100 is increased. Figure 5(d) shows this operation. As a result, the injection nozzle 52 is separated from the mold 100.

[0049] Thereafter, the valve pin 56 remains in the separated position until the start of the next injection process. When the injection process starts, the valve pin 56 is moved from the separated position to its retracted limit and resin is injected from the discharge port 52a of the injection nozzle 52.

[0050] [Third embodiment] In the second embodiment, an example has been described in which the valve pin 56 is on the molding machine side and the valve pin 111 is on the mold side, but the valve pin 56 and the valve pin 111 may be interchanged. The following description will be given with reference to Fig. 3 and each state of Fig. 6(a) to Fig. 6F.

[0051] In S35 in Fig. 3, the valve pin 56 starts moving from its retraction limit. Fig. 6(a) shows this operation. During the injection and pressure-holding steps, the valve pin 111 stops at its retraction limit in the resin flow path 114 of the hot runner. When pressure-holding is completed, the valve pin 111 starts moving in the direction to close the resin flow path 114.

[0052] In S36, the valve pin 56 comes into contact with the valve pin 111 and stops. Figure 6(b) shows this operation. The valve pin 111 passes through the resin flow path 114 in the hot runner, is inserted into the discharge port 52a of the injection nozzle 52, and comes into contact with the valve pin 56 and stops.

[0053] In S37, the valve pin 56 and the valve pin 111 move in close contact to the separation position and stop there. Figure 6(c) shows this operation. The valve pin 56 moves back toward the sprue bushing 105, and the valve pin 111 moves forward toward the discharge port 52a of the injection nozzle 52, moving to the separation position, i.e., the nozzle touch portion, and stopping there.

[0054] [Fourth embodiment] In the second and third embodiments, the tip shapes of the valve pin 56 and the valve pin 111 are described as being flat, but may be shapes other than flat. For example, the valve pin 56 may be configured as a convex curved surface shape and the valve pin 111 may be configured as a concave curved surface shape as shown in FIG. 7(a). In addition, when the valve pin 56 is configured as a cone shape and the valve pin 111 is configured as an inverted cone shape as shown in FIG. 7(b), the surface roughness of the valve pin 56 and the valve pin 111 may be adjusted to give a protruding shape to both sides as shown in FIG. 7(c). Although FIG. 7(a) and B show an example in which the valve pin 56 is convex and the abutment is concave, the concave and convex shapes may be reversed. In this way, if the tip of the valve pin 56 and the tip of the valve pin 111 are configured to fit into each other, leakage of resin can be suppressed.

[0055] <Injection molding machine> The configuration of the injection molding machine 2 will be described with reference to Fig. 1 as well as Fig. 8(a) to Fig. 9. Fig. 8(a) is a side view of the injection molding machine 2. Fig. 8(b) is an end view of the fixed platen 61, and is a perspective view of line II in Fig. 8(a). Fig. 9 is a partial perspective view showing the configuration around the molding operation position 11.

[0056] 1 and 8(a), an injection molding machine 2 includes an injection unit 5, a clamping unit 6, and a remover 7 that removes a resin molded product. The injection unit 5 and the clamping unit 6 are mounted on a frame 10 in the Y direction.

[0057] The injection device 5 includes an injection cylinder 51 extending in the Y direction. The injection cylinder 51 includes a heating device (not shown) such as a band heater, and melts the resin introduced from a hopper 53. A screw 51a is built into the injection cylinder 51, and the resin to be introduced into the injection cylinder 51 is plasticized and metered by the rotation of the screw 51a, and the molten resin can be injected from the injection nozzle 52 by the movement of the screw 51a in the axial direction (Y direction).

[0058] A shut-off nozzle capable of opening and closing the discharge port can be used as the injection nozzle 52. FIG. 8(a) shows an example of a shut-off nozzle. An opening and closing mechanism 57 of the shut-off nozzle in FIG. 8(a) is provided with a valve pin 56 that opens and closes the discharge port 52a. The valve pin 56 is connected to an actuator 57a (cylinder) via a link 57b. The valve pin 56 is operated by the operation of the actuator 57a, and the valve pin 56 opens and closes the discharge port 52a.

[0059] FIG. 8(a) shows the position of the tip 56a of the valve pin 56 when the valve pin 56 closes the resin flow path (discharge port 52a) of the injection nozzle 52. When the valve pin 56 moves to the rear limit, the valve pin 56 opens the resin flow path (discharge port 52a), and the tip 56a of the valve pin 56 moves to position 56b. FIG. 8(a) shows the position of the tip 52b of the injection nozzle 52 when the valve pin 56 opens the resin flow path (discharge port 52a). When the valve pin 56 moves to the forward limit, the tip 56a of the valve pin 56 moves to position 56c. When the valve pin 56 closes the resin flow path (discharge port 52a) of the injection nozzle 52, the valve pin 56 protrudes further than the tip 52b of the injection nozzle 52 when the resin flow path (discharge port 52a) of the injection nozzle 52 is opened. This allows the valve pin 56 to be inserted into the sprue 115 of the mold 100 as described above.

[0060] The injection cylinder 51 is supported by a drive unit 54. The drive unit 54 is provided with a plasticization metering motor that rotates the screw 51a and an injection motor that moves the screw 51a forward and backward in the axial direction. The drive unit 54 is capable of moving forward and backward in the Y direction along the rail 12 on the frame 10, and the drive unit 54 is provided with an actuator (e.g., an electric cylinder) 55 that moves the entire injection device 5 forward and backward in the Y direction.

[0061] The mold clamping device 6 is a device that clamps the mold 100 and opens and closes the mold, and in this embodiment, is a toggle-type mold clamping device. The mold clamping device 6 includes a fixed platen 61, a movable platen 62, and a movable platen 63 arranged in this order in the Y direction. A plurality of tie bars 64 (four in this embodiment) pass through these platens 61 to 63. Each tie bar 64 is a shaft that extends in the Y direction, and one end of the tie bar 64 is fixed to the fixed platen 61. Each tie bar 64 passes through a through hole formed in the movable platen 62. The other end of each tie bar 64 is fixed to the movable platen 63 via an adjustment mechanism 67. The movable platens 62 and 63 are movable in the Y direction along rails 13 on the frame 10, and the fixed platen 61 is fixed to the frame 10.

[0062] A toggle mechanism 65 is provided between the movable platen 62 and the movable platen 63. The toggle mechanism 65 is a mechanism that moves the movable platen 62 forward and backward in the Y direction relative to the movable platen 63 (in other words, relative to the fixed platen 61). The toggle mechanism 65 includes links 65a to 65c. The link 65a is rotatably connected to the movable platen 62. The link 65b is rotatably connected to the movable platen 63. The links 65a and 65b are rotatably connected to each other. The link 65c is rotatably connected to the link 65b. The link 65c is also rotatably connected to an arm 66c.

[0063] The arm 66c is fixed to a ball nut 66b. The ball nut 66b is engaged with a ball screw shaft 66a extending in the Y direction, and moves forward and backward in the Y direction by rotation of the ball screw shaft 66a. The ball screw shaft 66a is rotatably supported by the movable platen 63, and a motor 66 is supported by the movable platen 63. The motor 66 rotates the ball screw shaft 66a. The amount of rotation of the motor 66 is detected by a sensor (not shown) such as a rotary encoder. By driving the motor 66 while detecting the amount of rotation of the motor 66, the mold 100 can be clamped and opened / closed.

[0064] The injection molding machine 2 is equipped with a sensor 68 that measures the mold clamping force. In the case of this embodiment, the sensor 68 is a strain gauge provided on the tie bar 64, and detects the strain of the tie bar 64 to calculate the mold clamping force.

[0065] The adjustment mechanism 67 includes a nut 67b rotatably supported on the movable platen 63, a motor 67a as a drive source, and a transmission mechanism (here, a belt transmission mechanism) that transmits the drive force of the motor 67a to the nut 67b. Each tie bar 64 passes through a hole formed in the movable platen 63 and engages with the nut 67b. By rotating the nut 67b, the engagement position of the nut 67b and the tie bar 64 in the Y direction changes. That is, the fixed position of the movable platen 63 relative to the tie bar 64 changes. This makes it possible to change the interval between the movable platen 63 and the fixed platen 61, and to adjust the mold clamping force, etc. The rotation amount of the motor 67a is detected by a sensor (not shown) such as a rotary encoder. By driving the motor 67a while detecting the rotation amount of the motor 67a, the fixed position of the movable platen 63 relative to the tie bar 64 can be changed from the initial position to an arbitrary position with high accuracy.

[0066] The molding operation position 11 is an area between a pair of platens (a fixed platen 61 and a movable platen 62). The mold 100 introduced into the molding operation position 11 is clamped between the fixed platen 61 and the movable platen 62 and clamped. In addition, the movable platen 62 moves the movable mold 102 to open and close the mold.

[0067] 8(b), an opening 61a through which the injection nozzle 52 advances and retreats is formed in the center of the fixed platen 61. A plurality of rollers BR are rotatably supported on the surface of the fixed platen 61 facing the movable platen 62 (referred to as the inner surface). The plurality of rollers BR rotate about a rotation axis in the Y direction, and support the bottom surface of the mold 100 (the bottom surface of the mounting plate 101a), supporting the mold 100 from below and facilitating movement of the mold 100 in the X direction. Roller supports 620 are fixed to both sides of the fixed platen 61 in the X direction, and the roller supports 620 also support a plurality of rollers BR.

[0068] Grooves 61b extending in the X direction are formed on the inner surface of the fixed platen 61. The grooves 61b are formed in two rows spaced apart from each other vertically. A roller unit 640 is provided in each groove 61b. The roller unit 640 supports a plurality of rollers SR so that the rollers SR are rotatable. The rollers SR rotate about a rotation axis in the Z direction and come into contact with the side surface of the mold 100 (the side surface of the mounting plate 101a) to support the mold 100 from the side and guide the movement of the mold 100 in the X direction. As shown in the cross-sectional view of line II-II, the roller unit 640 is biased by a spring 641 to a position where the rollers SR protrude from the groove 61b, and when the mold is clamped, the roller unit 640 retracts into the groove 61b to a position where the rollers SR do not protrude into the groove 61b. The roller unit 640 can prevent the mold 100 from coming into contact with the inner surface of the fixed platen 61 and damaging the inner surface when replacing the mold 100, and does not interfere with the close contact between the inner surface of the fixed platen 61 and the mold 100 when clamping the mold.

[0069] Roller supports 630 are fixed to both sides of the stationary platen 61 in the X direction, and the roller supports 630 also support a plurality of rollers SR.

[0070] By using such rollers BR and SR, when the mold 100 is transported between the injection molding machine 2 and the transport device 3A or the transport device 3B, the mold 100 can be transported faster and more smoothly.

[0071] The stationary platen 61 is provided with a plurality of fixing mechanisms (clamps) 610 for locking the stationary mold 101 to the stationary platen 61. The clamps 610 are provided with an engaging portion 610a for engaging with the mounting plate 101a, and incorporate an actuator (not shown) for moving the engaging portion 610a between an engaged position and a disengaged position. The actuator is a fluid actuator such as a hydraulic actuator or an air actuator. An electromagnetic clamp may be used as a mechanism for fixing the mold. The electromagnetic clamp can magnetize or demagnetize the magnetic material inside the coil in a relatively short time by passing a current through the coil, and the mold can be attached and detached. However, if the mold 100 is to be frequently replaced, a fluid actuator is more advantageous.

[0072] Magnetization and demagnetization of an electromagnetic clamp are generally performed by instantaneously passing an electric charge stored in a large-capacity capacitor through a coil, but the current flowing through the coil is very large, and there is a problem that the coil and magnet gradually heat up if this is repeated many times. Since the magnetic force of a magnet weakens as the temperature rises and eventually loses its magnetic force, it is not desirable for the coil and magnet to heat up, and furthermore, the heat may be transmitted to the mold, affecting the quality of the resin molded product. One method to deal with this problem is to run cooling water through the electromagnetic clamp, but this is disadvantageous in terms of power consumption and equipment costs. Therefore, if the mold 100 is to be replaced frequently, a fluid actuator is more advantageous.

[0073] As with the fixed platen 61, the movable platen 62 is also provided with a plurality of rollers BR, roller supports 620 and 630, a roller unit 640, and a fixing mechanism 610 that locks the movable mold 102.

[0074] Please refer to Fig. 9. Generally, a door is provided around the mold clamping device, and when changing the mold, the door is opened to perform the change work. However, in this embodiment, it is assumed that the mold 100 will be changed frequently, and a configuration that requires opening and closing the door is inconvenient.

[0075] In the present embodiment, the clamping device 6 is surrounded by a cover (outer plate) 60, and an opening 60a is formed on the side of the molding operation position 11 to allow the mold 100 to pass through in order to replace the mold 100. The opening 60a is basically always open, allowing the mold 100 to be freely inserted and removed from the molding operation position 11. A manually opened and closed sliding door may be provided in the opening 60a to make the opening 60a closable. Then, during preparatory work such as replacing the mold 100 with another mold, the opening 60a may be closed by the sliding door.

[0076] Fig. 9 also shows an example of the appearance of the transport device 3B. A door may be provided on the frame 30 to separate the inside from the outside of the frame 30. In the example of Fig. 2(b), the controller 42B is disposed below the transport device 3B, but each controller may be disposed anywhere.

[0077] 8(a), the removal machine 7 will be described. The removal of the resin molded product can be performed by operating an ejector valve pin of the mold to automatically drop the resin molded product, or by a worker manually removing the resin molded product, but in this embodiment, the removal machine 7 is a mechanism for removing the resin molded product from the open movable mold 102.

[0078] The extractor 7 includes a rail 71 extending in the X direction and a movable rail 72 movable in the X direction on the rail 71. The movable rail 72 extends in the Y direction, and a slider 73 is provided on the movable rail 72. The slider 73 has a function of moving in the Y direction while being guided by the movable rail 72, and also has a function of raising and lowering a lifting shaft 73a in the Z direction.

[0079] A suction head 74 is provided at the lower end of the lifting shaft 73a, and a chuck plate 75 specialized for resin molded products is attached to the suction head 74.

[0080] After the molds are opened, the remover 7 moves the suction head 74 between the fixed mold 101 and the movable mold 102 by the rails 71, the movable rails 72, and the slider 73 as shown by the dashed lines in Fig. 8(a), and sucks up the resin molded product and transports it to the outside. Note that, although a suction-type remover is exemplified as the remover 7 in this embodiment, a remover that mechanically grips the resin molded product can also be used.

[0081] <Examples of resin molded product manufacturing> An example of the operation of the injection molding system 1 will be described. Fig. 10(a) is a flow chart showing an example of processing executed by the controller 41. Figs. 11 and 12 are diagrams showing an example of the operation of the injection molding system 1. The explanation will be given with reference to each step of the processing example in Fig. 10(a) and each state in Figs. 11 to 12. In the following example, it is assumed that molding operations are performed while switching between mold 100A and mold 100B, such as molding using mold 100A -> molding using mold 100B -> molding using mold 100A...

[0082] In S1 of FIG. 10(a), initial settings are performed. Here, the operating conditions of the injection unit 5 and the clamping unit 6 are registered for each of the molds 100A and 100B. For example, the initial values ​​of the amount of resin injected per time, temperature, injection speed, clamping force, and the position of the movable platen 63 relative to the tie bar 64 are included. These conditions may be the same or different for the molds 100A and 100B. Since the mold 100A is used for the first molding operation, first, the conditions related to the mold 100A are automatically set as the operating conditions. In addition, heating of the injection cylinder 51 and plasticization and metering of the initial resin are started.

[0083] In S2 of FIG. 10(a), the mold 100A is transported into the injection molding machine 2. FIG. 11 shows this operation. First, the motor 66 is driven to make the gap between the fixed platen 61 and the movable platen 62 slightly wider than the thickness (width in the Y direction) of the mold 100A as shown in state ST1. Next, the controller 41 transmits an instruction to carry in the mold 100A to the controller 42A, and the controller 42A drives the transport unit 31 to carry in the mold 100A to the molding operation position 11. When the carry-in is completed, a signal indicating the carry-in completion is transmitted from the controller 42A to the controller 41. When the signal indicating the carry-in completion is received, the motor 66 is driven to bring the fixed platen 61 and the movable platen 62 into close contact with the mold 100A. At this time, it is not necessary to generate a clamping force that is generated during molding.

[0084] In S3 of FIG. 10(a), the fixing mechanism 610 is driven to lock the mold 100A to the fixed platen 61 and the movable platen 62, respectively.

[0085] In S4 in Fig. 10(a), the motor 66 is driven to drive the toggle mechanism 65, and the fixed platen 61 and the movable platen 62 clamp the mold 100A. In S5 in Fig. 10(a), preparations for injection into the mold 100 are made. Here, the actuator 55 is driven to move the injection unit 5, and the injection nozzle 52 is brought into contact with the mold 100A. State ST3 in Fig. 11 shows these operations. State ST3 shows the injection process in which resin is injected from the injection nozzle 52 having the valve pin 56 into the cavity of the mold 100A through the resin flow path of the mold 100A.

[0086] Next, the processes of S6 and S7 in FIG. 10(a) are performed in parallel.

[0087] In S6, the molten resin is injected and pressure is maintained. In detail, the injection device 5 is driven to fill the cavity in the mold 100A with the molten resin from the injection nozzle 52, and the resin is further pushed in at high pressure to compensate for the volume reduction caused by the solidification of the resin. During the process of S6, the actual clamping force is measured by the sensor 68. During molding, the temperature of the mold 100A gradually increases, causing the mold 100A to thermally expand, and a difference may occur between the initial clamping force and the clamping force after a certain period of time has passed. Therefore, the clamping force at the next clamping can be corrected based on the measurement result of the sensor 68. The clamping force is adjusted by driving the motor 67 to adjust the position of the movable platen 63 relative to the tie bar 64. In this way, the initial value of the position of the movable platen 63 relative to the tie bar 64 is corrected according to the measurement result of the sensor 68 to adjust the clamping force, thereby improving the accuracy of the clamping force. The position adjustment of the movable platen 63 relative to the tie bar 64 may be performed at any timing (for example, at any timing of SX1, S9, SX2, or S14 to S16 in the flowchart of FIG. 5(a)).

[0088] In S7, the mold 100 is unlocked from the fixed platen 61 and the movable platen 62 by the fixing mechanism 610. It may take a certain amount of time (e.g., several seconds) to unlock the mold 100. By unlocking the mold 100 in parallel with the injection and pressure holding in S6, it is possible to perform mold replacement in S9 immediately after the processing of S6 is completed. Because the mold 100 is in a clamped state, releasing the lock on the platens 61 and 62 will not cause the mold 100 to fall or cause the relative positions of the fixed mold 101 and the movable mold 102 to shift.

[0089] This can improve productivity. Specifically, for example, in a configuration in which the process of S7 is performed after the process of S6, unlike this embodiment, it is assumed that the interval between removing resin molded products is 18 seconds and it takes 2.6 seconds to unlock the mold in S7. In this case, 4800 shots of resin molded products can be produced per day. On the other hand, if the processes of S6 and S7 are executed in parallel as in this embodiment, and the unlocking of the mold 100 can be completed during the process of S6, the interval between removing resin molded products can be shortened to 15.4 seconds. 5610 shots of resin molded products can be produced per day, and productivity is improved by 16.9%.

[0090] When the fixing mechanism 610 uses a fluid actuator as a driving source, a spring for holding the mold may be provided in the fixing mechanism 610 to prevent the mold 100 from falling off the injection molding machine 2 as a countermeasure in the event of a power outage or equipment trouble causing loss of fluid pressure. However, when such a spring is provided, the lock needs to be released against the biasing force of the spring, and the unlocking time tends to be longer. In particular, the unlocking time is longer in the case of a pneumatic actuator. When the mold 100 becomes larger, a stronger spring is used, and a fluid actuator with higher output is also used, but since high-output fluid actuators generally have a large-diameter cylinder, the unlocking time tends to be longer.

[0091] When the fixing mechanism 610 is driven by an electromagnetic clamp, it is possible to lock it in a short time by passing a large current through the coil. However, demagnetization for unlocking generally requires gradually weakening the magnetic force while applying an alternating current to the coil, so it takes a certain amount of time to unlock it.

[0092] By performing the processes of S6 and S7 in parallel as in this embodiment, the waiting time due to unlocking can be shortened. The unlocking of S7 may be started after the start of injection in S6 and before the start of dwelling pressure. By completing the unlocking of S7 before the completion of dwelling pressure, the waiting time before the start of the subsequent process (S9) can be set to zero. If the processing time of S6 is short, the unlocking of S7 will be completed after the completion of dwelling pressure, but the waiting time can still be shortened compared to the case where the process of S7 is executed after S6.

[0093] After the processes of S6 and S7 are completed, the processes of S8 to S10 are performed in parallel. In S8 of Fig. 10(a), timing of the cooling time of the resin molded product in the metal mold 100A is started.

[0094] In S9, the mold is replaced. Here, the motor 66 is driven to drive the toggle mechanism 65. This causes the mold clamping force to disappear, and the movable platen 62 is slightly spaced from the fixed platen 61, forming a gap that allows the mold to be replaced. State ST4 in FIG. 11 shows a state in which the movable platen 62 is slightly spaced from the fixed platen 61. Then, the mold is loaded and unloaded. Details will be described later with reference to FIG. 10(b).

[0095] In S10 in Fig. 10(a), processing related to the injection unit 5 is performed. For example, pressure hold suck back, nozzle shutoff, retraction of the injection unit 5, start of plasticization metering for the next injection, etc. are performed here. State ST4 in Fig. 8(a) shows a state in which the injection unit 5 is retracted (a state in which the injection nozzle 52 is retracted).

[0096] The pressure holding suck back and nozzle shut off are to prevent the injection nozzle 52 from moving away from the mold 100A and dripping of the molten resin. These processes may be performed before the movable platen 62 is moved slightly away from the fixed platen 61 in S9. The pressure holding suck back is to reduce the resin pressure in the injection cylinder 51 and the mold 100 by retracting the screw 51a after the pressure holding. The retracted position of the screw 51a in the pressure holding suck back may be managed as an absolute position, or may be managed as a relative position to the position of the screw 51a after the completion of the pressure holding. The screw 51a may be retracted until it is detected that the resin pressure measured by a load cell (not shown) installed in the injection device 5 has decreased to a predetermined pressure. The nozzle shut off is to close the discharge port 52a of the injection nozzle 52. In the example of FIG. 8(a), the discharge port 52a is closed by the valve pin 56. This operation can prevent the resin from leaking out. The accuracy of resin metering for the next injection can also be improved. Although the above process can reduce resin leakage to some extent, depending on the type of resin and the structure of the mold, long strings of resin may occur between the mold 100 and the injection nozzle 52. As in JP 2019-081346 A, a pressure-holding suck-back and a shut-off nozzle can be used to prevent resin leakage when the mold and the molding machine nozzle are separated when replacing the mold. In this case, if the amount of pressure-holding suck-back is too large, air is drawn into the flow path, causing the molded product to have a poor appearance due to silver streaks. In addition, with low-viscosity resins such as polypropylene, the resin remaining at the tip of the shut-off nozzle may be stretched when separated, causing stringing. To prevent this, a device for blowing air onto the injection nozzle 52 may be installed, but the resin remaining at the discharge port 52a of the injection nozzle 52 may solidify due to the blowing of air, and the solidified resin may cause cold slugs in the next molding. In this embodiment, by inserting the valve pin 56 into the resin flow path (sprue 115) of the mold 100, stringing of the resin can be suppressed.

[0097] Fig. 10(b) shows an example of the mold replacement process in S9. In S21 in Fig. 10(b), the fixed platen 61 and the movable platen 62 start to be separated from each other. Specifically, as described above, the motor 66 is driven to drive the toggle mechanism 65. This causes the mold clamping force to disappear, and the movable platen 62 is moved relative to the fixed platen 61. As described above, the purpose of this is to slightly separate the fixed platen 61 and the movable platen 62 to form a gap that allows the mold to be replaced, but in this embodiment, the process in S22 starts before the separation operation is completed.

[0098] In S22 in FIG. 10(b), the ejection of the mold 100 from the injection molding machine 2 and the ejection of the mold 100 from the injection molding machine 2 are started. Here, no matter what control method is generally used, it takes some time from approaching the target movement amount or absolute position to converging to the target. In addition, since the movable platen 62, which needs to bear a high mold clamping force, is generally relatively heavy, it is difficult to move or stop it suddenly when moving from the moving state to stopping. Then, if the movement of the movable platen 62 is almost completed, a gap that allows the mold to be replaced is formed. In this embodiment, the productivity can be improved by starting the replacement of the mold 100 before the separation between the fixed platen 61 and the movable platen 62 is completed. This can reduce the waiting time of about 0.1 to 0.3 seconds per mold replacement, for example. If it is assumed that the waiting time is 0.2 seconds and 6000 mold replacements are performed per day, the waiting time can be reduced by 20 minutes per day.

[0099] The timing to start carrying out the mold 100 in S22 is, for example, a timing at a position about 0.5 mm to 2 mm before the completion of the movement of the movable platen 62, but can be appropriately set through prior experiments, etc. Similarly, the timing to start carrying in the mold 100 outside the apparatus is a timing at a position about 0.5 mm to 2 mm before the completion of the movement of the movable platen 62, but can be appropriately set through prior experiments, etc. The timing to carry in and out the mold 100 may differ depending on the mold, etc., so it may be configured to be able to be arbitrarily set and changed.

[0100] 10B, the separation between the fixed platen 61 and the movable platen 62 is completed (the movement of the movable platen 62 is completed). Note that the completion of the separation between the fixed platen 61 and the movable platen 62 is monitored, and if an abnormality is confirmed, the mold replacement may be stopped. Examples of abnormalities include a case where the movable platen 62 has not reached the target position, or a case where an overload occurs in the transport device 3A or 3B.

[0101] In S24 in FIG. 10(b), the motor 66 is driven to drive the toggle mechanism 65 to start the movement of the movable platen 62, and the stationary platen 61 and the movable platen 62 start to approach each other. Here too, the productivity can be improved by starting the movement of the stationary platen 61 and the movable platen 62 during the movement before the completion of the loading of the mold 100. The timing at which the movable platen 62 starts to move is, for example, a timing at a position about 0.5 mm to 3 mm before the completion of the movement of the loaded mold 100, but can be appropriately set by prior experiments, etc. The timing at which the movable platen 62 starts to move with respect to the position of the loaded mold 100 differs depending on the mold closing speed, the performance of the transport devices 3A and 3B, the weight of the mold 100, etc., so it may be configured to be arbitrarily set and changed.

[0102] In S25 of FIG. 10(b), the removal of the mold 100 from the injection molding machine 2 and the introduction of the mold 100 outside the injection molding machine 2 are completed. In S26, the approach between the fixed platen 61 and the movable platen 62 is completed (the movement of the movable platen 62 is completed). The fixed platen 61 and the movable platen 62 are in close contact with the mold 100 introduced into the injection molding machine 2. At this time, it is not necessary to generate a mold clamping force that is generated during molding. The completion of the approach between the fixed platen 61 and the movable platen 62 may be monitored, and if an abnormality is confirmed, the mold replacement may be stopped. Examples of abnormalities include a case where the movable platen 62 has not reached the target position, or an overload is generated in the conveying device 3A or 3B. In S27, the fixing mechanism 610 is driven to lock the mold 100 introduced into the injection molding machine 2 to the fixed platen 61 and the movable platen 62, respectively. With the above, the mold replacement process of S9 is completed.

[0103] State ST5 in FIG. 11 shows a state in which the mold 100 is replaced. Here, the mold 100A is carried out from the molding operation position 11 to the conveying device 3A, and the mold 100B is carried from the conveying device 3B to the molding operation position 11. The controller 41 transmits an instruction to the controller 42A to carry out the mold 100A, and the controller 42A drives the conveying unit 31 to carry out the mold 100A from the molding operation position 11. When the carrying out is completed, the controller 42A transmits a signal indicating the carrying-in completion to the controller 41. The mold 100A is cooled on the conveying device 3A. At this time, the self-closing portion 103 functions to maintain the mold 100A in a closed state.

[0104] After or in parallel with the removal of the mold 100A, the controller 41 transmits an instruction to the controller 42B to carry in the mold 100B, and the controller 42B drives the transport unit 31 to carry in the mold 100B to the molding operation position 11. When the carry-in is completed, the controller 42B transmits a signal indicating the carry-in completion to the controller 41.

[0105] When a signal indicating completion of loading is received, conditions related to the mold 100B are set as the operating conditions for the molding operation in S11 of Fig. 10(a). For example, the thickness (width in the Y direction) and clamping force of the mold 100B are set as the operating conditions for this molding operation. In addition, molding conditions such as the injection speed corresponding to the mold 100B are set. Note that since switching molding conditions may take time, for example, the molding conditions may be switched simultaneously with the instruction to unload the mold 100A.

[0106] In S12 in FIG. 10(a), it is determined whether or not this is the first molding operation for the mold 100A and the mold 100B. If this is the first molding operation, the process returns to S4, and if this is a molding operation for the second or subsequent times, the process proceeds to S13. In the flow described above, this corresponds to the first molding operation, and the process returns to S4, and the processes of S4 to S7 are executed for the mold 100B. State ST6 in FIG. 11 shows the state of the processes of S4 and S5 for the mold 100B, and state ST7 in FIG. 11 shows the state of a part of S9 and the process of S10 for the mold 100B. State ST6 shows the injection process in which resin is injected from the injection nozzle 52 having the valve pin 56 into the cavity of the mold 100A through the resin flow path of the mold 100A.

[0107] After the processes of S4 to S7 for the mold 100B are executed, the mold 100B is carried out and the mold 100A is carried in at S9. State ST8 in Fig. 11 shows the state where the mold 100B is carried out and the mold 100A is carried in. The mold 100B is cooled on the conveying device 3B. It is determined in S12 that this is not the first time, and the process proceeds to S13.

[0108] In S13, it is determined whether the cooling of the mold 100A is completed based on whether the cooling time that was started in S8 has reached a specified time. If the cooling is completed, the processes of S14, S16, and S17 and the process of S15 are performed in parallel.

[0109] In S14, the motor 66 is driven to separate the movable platen 62 from the fixed platen 61. Since the fixed mold 101 is fixed to the fixed platen 61 by the fixing mechanism 610 and the movable mold 102 is fixed to the movable platen 62 by the fixing mechanism 610, the movable mold 102 is separated from the fixed mold 101, and the mold 100A is opened.

[0110] In S16, the remover 7 is driven to remove the resin molded product remaining on the movable mold 102 side of the mold 100A and transport it to the outside. State ST9 in Fig. 12 shows the mold opening operation of the mold 100A and the process of removing the resin molded product P from the mold 100A. The suction head 74 is moved to a position where the chuck plate 75 faces the resin molded product P, and the resin molded product P is sucked and held.

[0111] In S15, preparation for the next injection operation for the mold 100A is performed. This is the same process as S5. In S17, the mold 100A is clamped. State ST10 in FIG. 12 shows a process of injecting resin from the injection nozzle 52 into the cavity of the mold 100A through the resin flow path of the mold 100A when the mold 100A is clamped. After the resin molded product P is removed from the mold 100A in state ST9, the resin is injected into the mold 100A in state ST10 without replacing the mold 100, so the process can be carried out efficiently. After that, the process returns to S6 and S7 to repeat the same process, and the process proceeds as follows: injection and pressure holding for the mold 100A → replacement of the mold 100 (removal of the mold 100A and loading of the mold 100B) → removal of the resin molded product from the mold 100B. State ST11 in Fig. 12 indicates replacement of the mold 100, and state ST12 in Fig. 12 indicates a process of removing the resin molded product P from the mold 100B. Thereafter, states ST13 to ST16 occur which are similar to states ST5 to ST8 in Fig. 11. Thus, after state ST16, states occur which are similar to states ST9 to ST12.

[0112] As described above, in this embodiment, the cooling of the mold 100 is performed on the conveying device 3A or conveying device 3B outside the injection molding machine 2. Then, while one mold 100 is being cooled, the injection molding machine 2 performs various processes such as removal of the resin molded product, clamping, injection, and pressure holding for the other mold 100. Since the mold opening and removal of the resin molded product are performed by the injection molding machine 2, the conveying device 3A and conveying device 3B do not need to have a mold opening function and a resin molded product removal function. Therefore, it is possible to manufacture the resin molded product P by replacing a plurality of molds 100A and molds 100B in one injection molding machine 2 while suppressing an increase in the cost of the system.

[0113] In particular, if the cooling time required for one mold 100 is within the time required for all processes from the start of the mold exchange process, the removal process of the other mold, the injection process, the pressure holding process, and the completion of the mold exchange process again, productivity can be improved up to twice as much as normal molding. In other words, in addition to suppressing cost increases, there is the advantage of being able to achieve high productivity. Many of the resin molded products used for exterior parts and mechanism parts of automobiles, home appliances, office equipment, etc. have a wall thickness of several millimeters to ensure strength. For this reason, the cooling process takes up the longest time of all molding processes. It is not uncommon for the cooling time to reach 50% to 70% of the entire molding process. The above embodiment is particularly effective in improving the productivity of this type of resin molded product.

[0114] Even when the thickness is relatively thin, such as about 1 mm, the cooling process tends to be long for resin molded products that require high dimensional accuracy, resins that require high mold temperatures, or crystalline resins that take a long time to cool. In the above embodiment, it is possible to achieve nearly double the productivity while satisfying good appearance and dimensional accuracy for a wide range of resin molded products.

[0115] The metal mold 100A and the metal mold 100B may be metal molds for molding the same resin molded product, or may be metal molds for molding different resin molded products. Regardless of whether the resin molded products to be molded are the same or not, the thickness in the Y direction and the clamping force may differ between the metal mold 100A and the metal mold 100B. However, in the case of this embodiment, the fixing position of the movable platen 63 relative to the tie bar 64 can be changed by the adjustment mechanism 67, and after the metal molds are replaced (S9 in FIG. 10(a)), the setting is changed (S11 in FIG. 10(a)). Therefore, the mold clamping setting can be performed according to each metal mold.

[0116] When the mold 100A and the mold 100B are molds for molding different resin molded products, it may be necessary to replace the chuck plate 75 with one corresponding to the type of resin molded product. However, replacing the chuck plate 75 takes time, regardless of whether it is done manually or automatically.

[0117] Therefore, a chuck plate 75 having holding portions corresponding to different resin molded products may be used, and the chuck plate 75 may be displaced depending on the mold 100 from which the resin molded product is removed, so that the holding portion corresponding to the resin molded product faces the resin molded product.

[0118] Although an example in which two molds 100A and 100B are replaced has been described, three or more molds may be replaced. For example, a case in which three molds 100A to 100C are replaced will be described. The mold 100A is carried into the injection molding machine 2, and the resin molded product is removed, clamped, and injected and pressure-held. The mold 100A is carried out, and the mold 100B is carried into the injection molding machine 2, and the resin molded product is removed, clamped, and injected and pressure-held. The mold 100B is carried out, and the mold 100C is carried into the injection molding machine 2, and the resin molded product is removed, clamped, and injected and pressure-held. The mold 100C is carried out, and the mold 100A is carried into the injection molding machine 2, and the resin molded product is removed, clamped, and injected and pressure-held. The same procedure is repeated thereafter. A device for transporting the three molds 100A-100C can be used that lines them up in the X direction, supports them on a common support, and includes an actuator that moves the support in the X direction. In the case of this configuration example, when the mold 100C is unloaded and the mold 100A is loaded, the mold 100B temporarily passes through the inside of the injection molding machine 2.

[0119] Higher productivity can be achieved by carrying the mold 100 in and out in a short time. To achieve this, it is possible to use a higher output unit as the transport unit 31, but this would increase costs. Therefore, a balancer device that uses the gravity of the weight to assist the movement of the mold 100 may be provided.

[0120] Of course, in the same injection molding machine 2, the injection step, the intermediate step, and the removal of the resin molded product may be repeated exclusively for one mold without changing the mold.

[0121] In this embodiment, an example has been described in which one injection unit 5 is installed in the injection molding machine 2, but an injection molding machine 2 having two or more injection units 5 may be used. In this method, it is not necessary to change the molding conditions for each injection unit 5, and further, molding can be performed using different types of materials in multiple molds.

[0122] In this embodiment, a general injection molding method consisting of the steps of injection, pressure holding, cooling, and removal is applied to the mold 100, but a known molding technique such as foam molding, gas assist molding, or heat and cool molding may be combined with at least one of the molds. These molding methods generally require a long cooling time, so combining them with this embodiment is advantageous in terms of improving productivity.

[0123] During the molding cycle, a temperature regulator may be constantly connected to the mold 100 via piping. The temperature regulator regulates the temperature of the mold 100, for example, by circulating a fluid such as cooling water between the mold 100 and the temperature regulator. The temperature regulator may be a common temperature regulator for the molds 100A and 100B, or may be provided for each of the molds 100A and 100B. By providing a temperature regulator for each of the molds 100A and 100B, the temperatures of the molds 100A and 100B can be independently regulated.

[0124] During the molding cycle, electrical wiring may be constantly connected to the mold 100. The electrical wiring may include wiring for supplying power to a hot runner, wiring for sensor signals such as thermocouples and limit switches, etc.

[0125] The insertion and removal of the valve pin in the intermediate process described above can also be applied to the stack mold type injection molding die described in JP 2003-127186 A. In JP 2003-127186 A, the hot runner nozzle [9] corresponds to the injection nozzle in the above-mentioned embodiment, and the middle die [2] corresponds to the die 100 in the above-mentioned embodiment. In contrast to JP 2003-127186 A, a modification is made so that when the hot runner nozzle mouth

[10] is closed by the movable pin

[12] , the movable pin

[12] protrudes beyond the tip of the hot runner nozzle [9] when the hot runner nozzle mouth

[10] is opened. In the injection process, resin is injected from the hot runner nozzle [9] of the fixed die [1] having the movable pin

[12] through the resin passage [6, 11, 18] of the middle die [2] into the molding cavity [5] of the movable die [3]. In the intermediate process, the movable pin

[12] of the hot runner nozzle [9] is inserted into the resin passage

[18] and the movable pin

[12] of the hot runner nozzle [9] is removed from the resin passage

[18] .

[0126] The embodiments described above can be modified as appropriate without departing from the scope of the technical concept. The disclosure of this specification includes not only what is described in this specification, but also all matters that can be understood from this specification and the drawings attached to this specification.

[0127] Furthermore, the disclosure of this specification includes the complement of each concept described in this specification. In other words, if this specification contains a statement that "A is greater than B," for example, even if the statement that "A is not greater than B" is omitted, this specification can be said to disclose that "A is not greater than B." This is because when a statement that "A is greater than B" is made, it is assumed that the case in which "A is not greater than B" is taken into consideration. [Explanation of symbols]

[0128] 52 Injection nozzle 56 Valve pin 115 sprue 104 Cavity 100 Molds

Claims

1. 1. A method for manufacturing an article using injection molding, comprising the steps of: a first step of injecting a resin from an injection nozzle having a valve pin through a resin flow path in a first mold into a cavity of the first mold; a second step of inserting the valve pin of the injection nozzle into the resin flow path after the first step, removing the valve pin of the injection nozzle from the resin flow path, and starting to increase the distance between the injection nozzle and the first mold in a state in which the valve pin blocks the discharge port of the injection nozzle after the removal of the valve pin; A manufacturing method characterized by comprising, after the second step, a third step of injecting resin from the injection nozzle through a resin flow path in the second mold into the cavity of the second mold.

2. The manufacturing method according to claim 1 , wherein in the second step, the injection nozzle and the first mold are in contact with each other during the removal.

3. The manufacturing method according to claim 1 or 2, wherein the resin present in the resin flow path of the injection nozzle in the second step is injected in the third step.

4. The manufacturing method according to claim 1 , wherein the first mold has a cold runner structure.

5. The manufacturing method according to claim 1 , wherein the first mold has a hot runner structure.

6. The valve pin of the injection nozzle is a first valve pin, The method of claim 1 , wherein the first mold has a second valve pin.

7. 7. The manufacturing method according to claim 6, wherein in the second step, the second valve pin of the first mold is inserted into the discharge port of the injection nozzle, and the second valve pin of the first mold is removed from the discharge port.

8. 8. The manufacturing method according to claim 7, wherein in the second step, the second valve pin is removed while the first valve pin and the second valve pin are maintained in contact with each other.

9. The manufacturing method according to claim 1 , further comprising a fourth step of removing a resin molded product from the first mold after the third step.

10. a fifth step of injecting a resin from the injection nozzle through the resin flow path of the first mold into the cavity of the first mold after the fourth step; The manufacturing method according to claim 9 , further comprising a sixth step of removing a resin molded product from the second mold after the fifth step.

11. 1. A method for manufacturing an article using injection molding, comprising the steps of: A first step of injecting a resin from an injection nozzle having a valve pin through a resin flow path of the mold into a cavity of the mold; a second step of inserting the valve pin of the injection nozzle into the resin flow path after the first step, removing the valve pin of the injection nozzle from the resin flow path, and starting to increase the distance between the injection nozzle and the mold in a state in which the valve pin closes the discharge port of the injection nozzle after the removal, The manufacturing method is characterized in that the mold has a cold runner structure.

12. The valve pin of the injection nozzle is a first valve pin, The method of claim 11 , wherein the mold has a second valve pin.

13. A manufacturing method described in any one of claims 1 to 10, wherein the valve pin blocks the outlet of the injection nozzle during the period from when the injection nozzle is moved away from the first mold due to the increase to when the injection is performed in the third step.

14. In the second step, increasing the distance between the injection nozzle and the first mold in a first direction; The manufacturing method according to claim 1 , wherein the first mold and the second mold are transported in a second direction different from the first direction between the second step and the third step.

15. The method according to claim 11 or 12, wherein in the second step, the injection nozzle and the mold are in contact with each other during the removal.

16. The manufacturing method according to claim 6 , wherein in the second step, the first valve pin and the second valve pin come into contact with each other.

17. The manufacturing method according to claim 16, wherein in the second step, the first valve pin is removed while the first valve pin and the second valve pin are maintained in contact with each other.

18. 18. The manufacturing method according to claim 6, wherein in the second step, a tip of the first valve pin and a tip of the second valve pin are fitted into each other.

19. The manufacturing method according to claim 1 , wherein the second step includes a state in which a gap between the resin flow path of the injection nozzle and the resin flow path of the first mold is closed.

20. A manufacturing method described in any one of claims 1 to 19, wherein in the second step, the increase is achieved by moving the injection nozzle.

Images